Segmented composite bearings and wind generator utilizing hydraulic pump/motor combination

ABSTRACT

A bearing assembly and wind generator. The bearing assembly includes a plurality of bearing segments defining a sliding member and a bearing body, with the sliding member and bearing body being joined together, and the plurality of bearing segments being coupled together to define an annular bearing structure. Also, a wind generator includes a wind rotor supported upon a tower, a hydraulic pump coupled to the wind rotor, and with rotation of the hydraulic pump pressurizing a hydraulic fluid, and a hydraulic motor in fluid communication with the hydraulic pump, and an electrical generator driven by the hydraulic motor to produce electrical energy.

TECHNICAL FIELD

The present disclosure is generally directed to bearing technologies.More particularly, the disclosure relates to segmented bearings ofcomposite materials and manufacturing processes and applicationsincluding, but not limited to, wind generators and other heavyequipment. A variety of ring bearings may be manufactured utilizingaspects of the present invention. The disclosure also relates to analternative to the mechanical wind generator including utilization of ahydraulic pump/motor combination.

BACKGROUND OF THE INVENTION

Large diameter bearings suitable, for example, azimuth bearings forsupporting rotating equipment such as wind power generators aretypically formed from unitary components, such as bearing races.

Prior art azimuth bearings for wind generators typically undergononuniform loading. During the occasional movement in response tochanges of wind direction, high impulse-type loadings are applied to theazimuth bearings. Such impulse loadings often result in excess contactzone stresses leading to surface damage and eventual bearing failure.

Prior art wind power generators typically include a gear box andelectrical generator within the rotor housing supported upon the towerbase. The gear box and electrical generator are relatively heavy andrequire routine maintenance. Access to the housing is limited by theheight of the tower base. A need remains for a light-weight,less-complex approach to wind power generation.

SUMMARY OF THE INVENTION

The invention generally relates to processes and products of processesfor making segmented composite-material bearings. Embodiments of thepresent invention may be used for various purposes, though exceptionaladvantages can be attained when used for large diameter bearings, suchas azimuth bearings for supporting rotating parts of equipment such aswind towers for power generation. Therefore the invention will bediscussed in connection with such uses.

Embodiments of the present invention concern bearings for thetransmission of high axial forces and large flexural moments with smallrelative movements between the co-operating bearing components. Windpower installations would benefit with such a bearing between itspylon-supported machine head and the pylon head.

Bearings of the present invention involving the demand profile asspecified above can be used for example as pivot bearings in cranes,certain leisure and pleasure installations and indeed wind powerinstallations (as so-called azimuth bearings). In that respect, astructural problem arises out of the fact that, even in the case of avertical rotary axis, the forces, both in the direction of an appliedload and also in the lifting-off direction, have to be carried by thebearing.

Also included in this disclosure is a novel hydraulic fluid-based windgenerator and system of wind generators utilizing hydraulic pump/motorcombinations. In one embodiment, a one-to-one ratio exists between thehydraulic pump/motor combinations. In another embodiment, a singlehydraulic motor can be supplied pressurized hydraulic fluid from aplurality of hydraulic pumps associate with a plurality of wind rotors.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention in order that the detaileddescription of the invention that follows may be better understood.Additional features and advantages of the invention will be describedhereinafter which form the subject of the claims of the invention. Itshould be appreciated by those skilled in the art that the conceptionand specific embodiment disclosed may be readily utilized as a basis formodifying or designing other structures for carrying out the samepurposes of the present invention. It should also be realized by thoseskilled in the art that such equivalent constructions do not depart fromthe spirit and scope of the invention as set forth in the appendedclaims. The novel features which are believed to be characteristic ofthe invention, both as to its organization and method of operation,together with further objects and advantages will be better understoodfrom the following description when considered in connection with theaccompanying figures. It is to be expressly understood, however, thateach of the figures is provided for the purpose of illustration anddescription only and is not intended as a definition of the limits ofthe present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a wind generator within which a ring bearingassembly of the present invention is utilized.

FIG. 2 is a cut-away detailed portion of the wind generator of FIG. 1.

FIG. 3 is a depiction of an embodiment of a prior art wind generator.

FIG. 4 is a depiction of an embodiment of a hydraulic power-based windgenerator.

FIG. 5 is a depiction of an embodiment of a system of wind generators ofFIG. 4.

FIG. 6 is an exploded-view depiction of a bearing assembly according toan embodiment of the present invention.

FIG. 7 is a top view of the bearing assembly of FIG. 6.

FIG. 8 is a cross-sectional view of the bearing assembly of FIG. 6

FIG. 9 is a cross-sectional view of another embodiment of the bearingassembly of FIG. 6.

FIG. 10 is a cross-sectional view of another embodiment of the bearingassembly of FIG. 6.

FIG. 11 is a cross-sectional view of another embodiment of the bearingassembly of FIG. 6.

FIG. 12 is a perspective view of a bearing body segment of FIG. 6.

FIG. 13 is a perspective view of a bearing body segment of FIG. 12including a sliding member.

FIG. 14 is a cross-sectional view of the bearing of FIG. 7 taken alonglines B-B.

FIG. 15 is a cross sectional view of a bearing embodiment including aself-locking feature.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to products and processes for making segmentedcomposite-material bearings. Embodiments of the present invention may beused for various purposes, though exceptional advantages can be attainedwhen used for large diameter bearings, such as azimuth bearings forsupporting rotating parts of equipment such as wind towers for powergeneration. Therefore the invention will be discussed in connection withsuch uses.

Generally, a wind turbine includes a rotor having multiple blades. Therotor is mounted to a housing or nacelle, which is positioned on top ofa truss or tubular tower. Utility grade wind turbines (i.e., windturbines designed to provide electrical power to a utility grid) canhave large rotors (e.g., 30 or more meters in diameter). Blades on theserotors transform wind energy into a rotational torque or force thatdrives one or more generators that may be rotationally coupled to therotor through a gearbox. The gearbox steps up the inherently lowrotational speed of the turbine rotor for the generator to efficientlyconvert mechanical energy to electrical energy, which is fed into autility grid.

In some configurations and referring to FIGS. 1 and 2, a wind turbine500 comprises a nacelle 502 housing a generator. Nacelle 502 is mountedatop a tall tower 504, only a portion of which is shown in FIG. 1. Windturbine 500 also comprises a rotor 506 that includes one or more rotorblades 508 attached to a rotating hub 510. Although wind turbine 500illustrated in FIG. 1 includes three rotor blades 508, there are nospecific limits on the number of rotor blades 508 required by thepresent invention. The drive train of the wind turbine includes a mainrotor shaft 516 (also referred to as a “low speed shaft”) connected tohub 510 via main bearing 530 and (in some configurations), at anopposite end of shaft 516 to a gear box 518. Gear box 518 drives a highspeed shaft of generator 520. In other configurations, main rotor shaft516 is coupled directly to generator 520. Yaw drive 524 and yaw deck 526provide a yaw orientation system for wind turbine 500. A large azimuthbearing 530 is positioned between yaw deck 526 and tower 504. Yawbearing 530 orients the nacelle toward the direction of the wind. Yawbearing 530 mainly executes adjusting movements. Extreme load cases aredefined to occur rarely during the service life of the bearing.

The efficiency of a wind turbine depends on many parameters includingthe orientation of the nacelle, or more specifically the location of therotor plane with respect to the direction of the air stream. This istypically controlled by the yaw drive or azimuth-drive, which orientsthe nacelle into the wind. In modern wind turbines electrical andmechanical components form a yaw drive. More specifically, an electrichigh-speed drive motor is coupled by a gear reducer having a drivepinion gear engaging a bull gear. Usually the electric drive motor, thegear reducer, and the drive pinion gear are mounted on the nacelle'sbedplate while the bull gear is fixed to the tower.

It will thus be observed that configurations of the present inventionprovide wind turbines with azimuth bearings that are cost effectivelymanufactured. Moreover, some configurations of the present inventionwill also be observed to provide other advantages, such as light weightconstruction and efficient interchangeability during repair orreplacement.

Besides the rotational energy delivered to the generator and convertedto electrical energy, other loads and forces act of the system. Forexample, substantial loads are transmitted over the tower head and thefoundation.

FIG. 3 depicts a wind generator assembly providing a mechanicaltransformation between wind energy and electrical energy via the rotor600, gear box and generator 602. In a typical application the gear boxand generator 602 are located within the rotor housing 604. Electricalenergy 606 is transmitted from the rotor housing via electricalconductors. The gear box and generator 602 and housing 604 are supportedupon tower 608 via azimuth bearing 610.

In comparison to the above-described mechanical approach of convertinginherently low rotational speed of the wind turbine rotor, a hydraulicfluid transformation offers another, very flexible and may be even moreappropriate approach. FIG. 4 illustrates an alternative equivalenthydraulic approach where a hydro-mechanical gear box and generator 702are positioned away from the rotor housing 704. A hydraulic motor/pumpcombination is utilized wherein a hydraulic pump 703 is located in therotor housing 704 and the motor and generator 702 are located away fromthe rotor housing 704, such as at the tower base or even more remotelyspaced from the rotor housing. Azimuth bearing 710 supports the housing704 upon tower 708. The wind-driven rotor 700 drives the pump 703 todeliver pressurized hydraulic fluid 706 to the generator 702. Hydraulicfluid lines 706 provide fluid communication between the pump 703 and thegenerator 702. One significant benefit of such an approach is thereduction in weight carried by the rotor housing 704 and tower 708 asthe motor/electrical generator may be ground supported. The reduction inweight achieve by the hydro-mechanical approach may allow for lighterand less expensive wind generators.

In the embodiment of FIG. 4, a one-to-one relationship exists betweenthe pump and motor. In another approach, such as shown in FIG. 5, acluster of hydraulic turbine towers 708 feed hydraulic energy to acentral hydraulic transformation unit 800. In this regard, onehydro-mechanical electrical generator can be utilized with several windtowers. Cost savings realized via such an approach may be significant.

For both versions, the mechanical and the hydraulic-based, there maystill be a significant weight on located atop the wind turbine towerwhich may dictate the use of azimuth bearings in general. Bearings ofsuch as described in this application are designed to optimize theperformance, durability and long term benefit of this wind powertechnology.

Referring now to FIGS. 6-14, embodiments of bearing assemblies inaccordance with the invention will be described. As will be appreciatedbased on this disclosure, advantages of segmented bearings in accordancewith the present invention include: the provision of a sliding memberhaving a low coefficient of friction bearing surfaces through the use ofPTFE or related polymer materials, incorporation of a rigid body forsupporting the sliding member of PTFE or related polymer materials, andan ability of the bearing to self-adjust in response to load conditionsand/or bearing support conditions yielded from the bearing'sflexibility, at the same time increasing the overall tower or systemflexibility and ability to adjust to the given conditions instead ofwithstanding those given conditions.

FIG. 6 illustrates an exploded perspective view of a segmented bearingring 8 including top ring 10, a plurality of bearing segments 12, bottomring 14 and bearing support 16, comprised such as a plurality of ballbearings, resilient rubber-like material or fluid-filled supports.Housing ring 18 includes a circular channel 20 into which bearingcomponents are received. An external or internal surface of housing ring18 may be machined to define gears.

Bearing segments 12 include one or more sliding members 19 forsupporting a bearing load in a sliding manner. As described in moredetail hereinafter, bearing segments 12 include a relatively-rigidbearing support and a sliding member 19 of a low coefficient of frictionmaterial. Bearing segments 12 are held within housing ring 18 via aplurality of fasteners 22.

FIG. 7 is a top plan view of the bearing ring 8 of FIG. 6 furtherillustrating the plurality of fasteners 22 for securing bearing segments12 to bearing housing ring 18. Fasteners 22 may be threaded fasteners orinclude other mechanical structures.

FIG. 8 is a cross-sectional view of the bearing ring 8 of FIG. 7 takenalong lines A-A. Bearing support 16 may include a rubber-like padcontaining fluid or liquid and/or solid bearing materials, such as ballbearings, depending on the desired load applications. Bearing support 16may include an elastomeric bearing pad to more readily adapt to movementof the load carrying members, whether as a result of temperature changeor as a result of varying wind loads. Further, complexity of movement ofthe load carrying members with respect to the wind generator support maybe of limited consequence as the bearing support 16 is desirably free tolean and tilt and to move, thereby to adapt to complex movements withoutdifficulty. In one embodiment of the present invention, bearing support16 comprises an elastomeric main body portion of rubber or of asynthetic rubber, such as chloroprene, urethane rubber or the like.

FIG. 9 is a cross-sectional view of bearing ring 8 showing analternative embodiment of bearing support 16 including a plurality ofball bearings 30. The sizing and quantity of ball bearings 30 would bedependent on the desired load applications. One benefit of theball-bearing, air, liquid or solid elastomer based support 16 is theability of the bearing 8 to self-adjust as load and/or supportconditions vary. Bearing support 16 may be functionally similar to thebearing block technology disclosed in PCT Int. App. PCT/EP93/03028,published as WO 94/10468 to J. Corts.

FIG. 10 is a cross-sectional view of bearing ring 8 showing analternative embodiment of bearing segment 12. In this embodiment,bearing segment 12 is provided with upper and lower sliding bearingsurfaces 32, 34. In a similar embodiment of the present invention,bearing support 16 is not present and the bearing segment having a pairof bearing surfaces 32, 34 directly engages other bearing surfaces in asliding manner.

FIG. 11 is another cross-sectional view of bearing ring 8 whereinbearing housing ring 18 is open-ended. Additionally, bearing segments 12are retained within housing ring 18 by one or more hold-down rings 36.

FIG. 12 is a perspective view of bearing segment 12 showing body 40.FIG. 13 is a perspective view of a bearing segment 12 showing lowfriction sliding member 19 and support body 40. Support body 40 ispreferably of metal construction, such as of a bronze or other material,and includes a plurality of holes or apertures. Support body 40 may bemade of a variety of different relatively rigid materials, including butnot limited to metals and non-metals. Support body 40 is adapted todefine a fail-safe mechanism in the event sliding member 19 is destroyedor damaged during use.

Therefore, bearing segments 12 each include bearing body 40 and slidingmember 19 defining a sliding bearing surface. Bearing body 40 preferablycomprises metal material having given strength, the properties of whichis not restricted essentially. One important aspect of the presentinvention is that bearing body 40 provides a fail-safe structure in theevent of loss or destruction of sliding member 19.

FIG. 14 is a cross-sectional view of bearing ring 8 taken across linesB-B in FIG. 7. Due to the fact that certain PTFE-based materials have anextremely low coefficient of friction it is difficult to fix suchmaterials to an underlying bearing support body 40. Addressing thislimitation, bearing segments 12 each include a support body 40 havingretention structure 42 to assist in securing the sliding member 19 tosupport body 40. Retention structure 42 provides a mechanical lock toprevent the sliding member 19 from separating from support body 40during use. A variety of different retention structure surfaces would bepracticable in alternative embodiments of the present invention.

Various embodiments of the present invention describe a mechanicalconnection between PTFE-based sliding member 19 and support body 40. Theprior art includes German patent no. 9315675.8, originally assigned toMACOR Marine Systems, Bremen, Germany, and incorporated by referenceherein. Additional teachings of PTFE-based bearings are found in PCTInternational Application WO/98/35873, to J. Corts, and incorporatedherein for all purposes.

Sliding member 19 preferably comprises a material with self-lubricityand the material composing the sliding member 19 may be a self-lubricityorganic material or inorganic material or the combined material withself-lubricity. Hereinafter, the “self-lubricity material” or “materialwith self-lubricity” shall have low friction coefficient. The reason ofusing “self-lubricity material” for a material of the sliding member 19is based on the fact that the bearing body 40 is positioned on a plateor pad fixed on a base, should be smoothly sliding on the plate or padduring operation of the associated equipment, e.g., the wind turbine.

The self-lubricity material is applied to one or more sides of thebearing body 40 facing and contacting to pad/plate bearing surfaces soas to form a smooth sliding between the bearing 8 and the supportpad/plate. Further, by applying such self-lubricity material, thenecessity of inserting a lubricant between can be removed so as toreduce much the cost of maintenance.

The self-lubricity material to be applied has preferably less than 0.30of the friction coefficient between the sliding member 19 and thebearing support surfaces. This will enable smooth sliding between thebearing surfaces, even in the view of changes of the alignment due to avariety of sources. The friction coefficient may be more preferably lessthan 0.20.

An organic material with self-lubricity may be a resin material withself-lubricity. There may be listed for resin material withself-lubricity to be applied on the sliding member 19 for example, PTFE,ethylene tetrafluoride, ethylene tetrafluoride perfluoro alkoxyethylene, polyether ether ketone and polyimido having low frictioncoefficient. Those materials can be used solely or in the combination.Suitable materials for sliding member 19 may also include high densitypolyethylene (HDPE) or ultra high molecular weight polyethylene(UHMWPE). Other suitable sliding member 19 materials may comprise filledcompositions, such as those incorporating graphite or reinforcingagents, such as glass fibers, and fabrics, such as woven or non-wovenfabrics. For example, sliding member 19 may include fiber-based plainbearings utilizing fiber reinforcement technology as disclosed in Pat.No. DE 4439887, filed Nov. 8, 1994, said document being incorporatedherein by reference. As a result, the self-lubricity material formingthe sliding member 19 may be sole material with the self-lubricity, orthe self-lubricity material reinforced with reinforcing material(composite). The reinforcing material may be glass fibers, carbonfibers, graphite fibers or ceramic fibers or the particulate materialthereof. The content of the reinforcing material can be changeddepending on bearing load requirements.

In one embodiment of the present invention, sliding member 19 is formedof a fluorine-based resin such as polytetrafluoroethylene (PTFE), andPTFE may be used solely or as a mixture with glass fibers or molybdenumdisulfide. It is also possible to form a laminated structure whichcomprises a layer of PTFE only and a layer of PTFE mixed with glassfibers or molybdenum disulfide. When the sliding member 19 is disposedon the side of the bearing body 40, PTFE can be charged into the holesor openings with ease, and the sliding surface is good in abrasionresistance due to the low coefficient of friction and a good slidingproperty of PTFE.

In the sliding member 19 described above, the fluorine-based resin layermade of PTFE or a mixture of PTFE and glass fibers or molybdenumdisulfide can be bonded uniformly to the bearing body 40 with a highstrength. Therefore, reliability of the sliding member 19 and of variousdevices using it can be enhanced remarkably.

The compression elasticity modulus (E) of the material withself-lubricity is preferably more than 500 MPa. By using the materialhaving the compression elasticity modulus (E) more than 500 MPa, thedeformation due to the weight of the wind turbine components can becontrolled and further, the shifts in the alignment can be accommodated.

As described above, the bearing body 40 and the sliding member 19 can bejoined by means of mechanical binding. Compression molding or injectionmolding of the self-lubricity material on the surface of the bearingbody 40 can be used to mechanically and thermally couple the slidingmember 19 to the bearing body 40. Those technologies can be selecteddepending on the properties of the self-lubricity material to be formed.

As described above, a portion of a sliding material 19 is inlaid in thebearing body 40 to make the bearing segment 12 by applying a combinationof heat and pressure to self-lubricity material to form the slidingsurfaces of the self-lubricity material on the bearing body 40.Retention structure 42 are preferably formed on surfaces of the bearingbody 40 so that they are filled with a portion of the self-lubricitymaterial to form the sliding member 19 of the self-lubricity materialand provide further the wedge effect by the filled self-lubricitymaterial to control or reduce the dislocation and release between thebearing body 40 and the sliding member 19.

In one embodiment, openings formed in the bearing body 40 are filledwith self-lubricity material. The openings are filled and cured withmaterial with self-lubricity so as to form the sliding surface of theself-lubricity material thereon. As described above, the sliding member19 can be prevented from release and dislocation by the wedges as formedby the retention structure 42 to securely fix the sliding member 19 tothe bearing body 40. In one bearing embodiment, such as described above,the bearing body 40 has large porosity (holes, apertures, channels,slots, etc.) and is a relatively complex structure in the form ofthree-dimensional network. When the sliding material is charged orthermally formed into the porous bearing body 40, the contact areabetween the bearing body 40 and sliding member 19 can be determinedlarge, and a good wedge effect can be obtained. In other words, sincethe porous bearing body 40 and sliding member 19 coupled therein aremutually engaged in a complex form against a tensile direction, a highwedge effect is exerted to enhance a bonded state, and the contact areacan be increased substantially to improve connection properties between,for example, PTFE and a metal bearing body.

Segmented annular bearings of the present invention are well suited forthe transmission of high axial forces and large flexural moments withsmall relative movements between the co-operating bearing components. Awind power installation may include such a bearing between itspylon-supported machine head and the pylon head. Bearings of the presentinvention involving the demand profile as specified above can be usedfor example as pivot bearings in cranes or other large equipment, suchas rotating machines at amusement facilities etc.

There is noted that the above mentioned embodiment of the presentinvention is illustrated in case of a segmented bearing using aself-lubricity material, but the other self-lubricity material can beapplied to the structure of the bearing body 40 in use for windgenerators, and the selection and choice of the material and thestructure of the bearing body 40 can be appropriately done from varietyof the materials.

The rotary bearing which is generally referred to as an azimuth bearingmakes it possible—by means of the tracking drive—to adjust the rotorwhich receives the wind power, in such a way that, depending on therespective wind direction, the highest level of efficiency is achievedand in addition, when the installation is stopped, the loading on allcomponents of the installation is kept as low as possible. Usually, therotary bearing which must be of large diameter in high-output wind powerinstallations comprises a rotary ball-type connection. A bearingaccording to the invention is substantially better suited to carryinghigh forces when small movements are involved. The bearings inaccordance with the present invention can carry vertical forces whichoccur in the axial direction both in the direction of an applied loadand also in the lifting-off direction. FIG. 15 discloses one embodimentof a self-locking version of a bearing assembly incorporating aspects ofthe present invention in which the bearing assembly is secured againstuplift. In such an example, multiple sliding members are provided,including a center sliding member and two or more external slidingmembers.

Although the present invention and its advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the invention. Moreover, the scope of the present applicationis not intended to be limited to the particular embodiments of theprocess, machine, manufacture, composition of matter, means, methods andsteps described in the specification. As one of ordinary skill in theart will readily appreciate from the disclosure of the presentinvention, processes, machines, manufacture, compositions of matter,means, methods, or steps, presently existing or later to be developedthat perform substantially the same function or achieve substantiallythe same result as the corresponding embodiments described herein may beutilized according to the present invention.

1-26. (canceled)
 27. A segmented ring bearing comprising: a plurality ofbearing segments with each bearing segment comprising a non-metallicsliding member and a metal bearing body; an annular ring supporting theplurality of bearing segments; a ring housing carrying the annular ringand plurality of bearing segments; and a bearing support positionedbetween the annular ring and a surface of the ring housing, said bearingsupport having flexibility to accommodate changes in alignment of theplurality of bearing segments during use.
 28. A segmented ring bearingcomprising: a plurality of bearing segments with each of said pluralityof bearing segments comprising a bearing body and a non-metallic slidingmember; an annular ring positioned to engage the plurality of slidingmembers; and a bearing housing for mechanically coupling the pluralityof bearing segments into the shape of a ring, wherein at least some ofthe plurality of bearing segments include a retention structure adaptedto receive a portion of the sliding member.